Mainil J G, Moseley S L, Schneider R A, Sutch K, Casey T A, Moon H W
Am J Vet Res. 1986 May;47(5):1145-8.
Colony hybridizations with 4 enterotoxins (STaP, STaH, STb, and LT) and 1 adherence factor (K99) gene probes were done on Escherichia coli isolated from calves. Agreement between the K99 probing and a serologic assay to detect the K99 antigen was 99% for the identification of K99+ and K99- isolates. Ninety-five of the isolates (22%) hybridized with at least 1 enterotoxin gene probe (Ent+ isolates), and 82 (19%), with the K99 gene probe. The majority of Ent+ isolates (85%) reacted with probes for STaP and K99 genes. The STaP gene was present by itself in 4 of the Ent+ isolates (4%) and with the STb gene in 6 of the Ent+ isolates (6%). Five of the Ent+ isolates (5%) carried the STb and LT genes, and none (0%) of the isolates carried the STaH gene. All but 2 of the isolates with the K99 gene also had the STaP gene. Twenty-eight isolates shown to produce STa enterotoxin in previous studies failed to hybridize with any of the enterotoxin gene probes. These 28 isolates were also phenotypically negative when the tests for enterotoxin production were repeated. These isolates probably lost their genes for enterotoxin production during storage in the laboratory.
对从犊牛分离出的大肠杆菌进行了与4种肠毒素（耐热肠毒素P、耐热肠毒素H、不耐热肠毒素和热稳定肠毒素b）和1种黏附因子（K99）基因探针的菌落杂交。在鉴定K99阳性和K99阴性分离株时，K99探针检测与检测K99抗原的血清学检测之间的一致性为99%。95株分离株（22%）与至少1种肠毒素基因探针杂交（肠毒素阳性分离株），82株（19%）与K99基因探针杂交。大多数肠毒素阳性分离株（85%）与耐热肠毒素P和K99基因的探针发生反应。耐热肠毒素P基因单独存在于4株肠毒素阳性分离株（4%）中，与热稳定肠毒素b基因共同存在于6株肠毒素阳性分离株（6%）中。5株肠毒素阳性分离株（5%）携带热稳定肠毒素b和不耐热肠毒素基因，无分离株（0%）携带耐热肠毒素H基因。除2株外，所有携带K99基因的分离株也都有耐热肠毒素P基因。在之前的研究中显示产生耐热肠毒素a的28株分离株未能与任何肠毒素基因探针杂交。当重复进行肠毒素产生检测时，这28株分离株在表型上也为阴性。这些分离株可能在实验室保存期间失去了产生肠毒素的基因。
